alt Hacker NewsDoing bitwise operations directly on raw pointers is a fast track to Undefined Behavior in standard C/C++. Emacs gets away with it largely due to its age, its heavy reliance on specific GCC behaviors/extensions, and how its build system configures compiler optimizations.
In modern C++, the technically "correct" and safe way to spell this trick is exactly as you suggested: using uintptr_t (or intptr_t).
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shadowgovt • today at 3:07 PM
Is there a similar solution to doing this in Rust? I suppose inside `unsafe` you can do basically anything.
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There’s a paper in flight to add a stdlib type to handle pointer tagging as well while preserving pointer provenance and so-forth. It’s currently best to use the intptr types, but the goal is to make it so that an implementation can provide specializations based on what bits of a pointer are insignificant, or even ignored, on a given target without user code having to be specialized. Not sure where it has landed since discussion in SG1 but seemed like a good idea.